There are several disease states and injuries for which it is desirable to remove fluids from the chest cavity of the afflicted individual. Clinicians monitor the amount of fluid removed in order to determine the progression of the healing process, the progression of the disease and the function of the devices used to effect such drainage. Typically, the patient has a drainage tube inserted into the chest cavity and the tube drains into a special closed container known as a chest drain unit (CDU). There are various means to measure the fluid in the sealed container and each is associated with a cost, either in clinician time in making an observation or measurement, or in equipment cost in providing sensors and signaling devices for making a measurement and bringing the measurement data to the attention of the clinician or a hospital information system.
For example, without limitation, some devices feature one or more strain gauges for measuring the weight or changing weight of a container. As the accuracy of the strain gauge increases, the gauge becomes more expensive and more susceptible to damage. Strain gauges in particular are easily damaged, and if designed to be more robust have less resolution to weight change.
Clinical staff monitoring of a patient on a CDU, required to record fluid drainage volume levels of a patient, is awkward, time consuming and, therefore, costly and not measured or checked as often as otherwise might be desirable. The drainage devices are usually kept on the floor and require a clinician to get down on hands and knees to read the fluid levels, and remember to adjust for errors should for instance the CDU accidentally be knocked over during use.